A few weeks ago I got into an unusual conversation with a guy in a coffee shop. We were both passing through town – he for personal travel and me for business. We struck up a conversation waiting in line and ended up chatting for the remainder of our respective stops there. We talked about what we did, where we were headed, etc. When I mentioned the blog and the PB philosophy behind it, his face lit up. He loved the idea and had embraced similar principles several years prior. His latest experiment, the health effects of which he raved about, was adding dirt to his diet. I listened with interest and asked questions.

On the one hand, how more fundamental can it get than ingesting earth – the very source of sustenance (in one way or another)? There’s minerals, probiotics, and all manner of goodies to be had. On the other hand – lest we forget the more savage side of ecology – there are the less hospitable microbes, the more insidious creepy crawlies – (roundworm, anyone?). Though my conversation partner that day explained with pride and assurance that he obtained his dietary dirt from only the most trusted, meticulous, and local purveyor, I wondered if I could get past the Fear Factor element. He seemed so taken by its effects – the weight loss, the improved digestion, the higher energy. With some careful caveats, could it be worth eating dirt?

In truth, humans have been eating earth for as long as we’ve been around – and not just because Grok didn’t have a salad spinner. Geophagy has been observed throughout the world – everywhere from sub-Saharan Africa to Europe, Asia to Australia. In the U.S., geophagy has figured into the culture of various indigenous cultures and to the past (and present) of the South, where experts believe native Africans who were brought as slaves introduced the practice.

It’s not just one of collective humanity’s hobby horses either. Scientists have studied geophagy in a host of other mammals as well, including elephants, wolves, and primates. Surely, this common a practice must have some kind of adaptive element?

A recent article from Lapham’s Quarterly traced the unusual, circuitous, and sometimes unsettling practice of geophagy in human history. (Those of you who count among your passions both history and food will appreciate the publication’s summer issue.) From a scientific angle, our understanding of geophagy has involved its crucial distinction from pica, the consumption of all varieties of non-edibles like coins, hair, soap, etc. Our view has also been colored by the interplay of cultures, the character of terrain and its vegetation, and the division between scientific and traditional approaches to health.

The article traces at length the career of Alexander Humboldt, an 18th and 19th century explorer, who first noted geophagy in the native population of a South American mission he visited. The indigenous Otomacs, Humboldt noted, ate a “‘prodigious quantity’” of “‘soft, unctuous clay” (which they called poya) that they obtained from particular areas of a nearby river bank. In fact, they not only ate it but meticulously collected it for routine seasonal storage. Humboldt was both floored and disgusted. Nonetheless, he was apparently hooked from then on. In the proceeding decades, he continued to study geophagy as it was observed around the world. His research “normalized” geophagy to the extent that people learned to associate it less with abnormal psychology and more with long-standing tradition across the globe, even in regions as “civilized” as Sweden and Finland.

Fast forward a couple centuries, and we’re still digging for the physiological roots of geophagy – the why. The who is pretty clear. Experts have noted that children and pregnant/child-bearing aged women are the most likely to practice geophagy, but it’s not limited to these demographics. As for the what, geophagy related earth is generally clay rather than soil. Where? How? Those who practice geophagy as their ancestors did in the same regions are as particular as the Otomacs were in harvesting said clay. Tribal/community wisdom passed down through the generations directs them to very specific sites. Usually, the clay is gathered by digging down a number of several inches – where microbial presence is substantially diminished compared to surface soil. Sometimes it is eaten as is. Other times it is mixed with water and used as a dip for food.

But why? Theories have abounded in scientific corners. Many experts traced the phenomenon to mineral supplementation. In other words, animals and humans ate earth to benefit from the nutrition of it – particularly minerals like calcium and iron. Numerous studies exist attempting to correlate anemia and earth eating. Some show that those who eat earth tend to be more iron deficient, but the earth routinely eaten by some of these groups is actually high in iron. More questions arise from there. Is something in the earth they eat interfering with iron absorption? Were they already deficient before they started eating earth? Which came first: the chicken or the egg? Moreover, when anemic, geophagy-practicing children in one study were given iron supplementation, they still ate the clay. Is it culture then? Habit? Is it something else biological – or all of the above?

When scientists sampled earth from geophagic sites frequented by animals, they found that the earth contained only modest mineral content. In another study, however, scientists carefully compared earth samples taken directly from where the animals ate (“interior” earth) with those taken at the surface/other spots at the site. The samples taken where the animals had eaten actually showed more mineral content. (Now that’s a discerning palate!)

Just a few weeks ago, a meta-analysis on geophagy research was published that goes a long way in honing in on the sense behind the practice. Sera Young from Cornell University and her fellow researchers analyzed more than 300 recorded observations of animal geophagy and nearly 500 of human geophagy instances. The records related to particular practices, soil content, etc. pointed to a rationale that’s been gaining momentum in the past two decades.

Instead of hunger of mineral supplementation, Young and her team found the most compelling support for geophagy as digestive protection and support. Those who engage in geophagy the most often (children and pregnant women), the researchers noted, are the most “vulnerable” to “dietary chemicals, parasites, and pathogens.” The clays routinely eaten in geophagic practice showed little overall mineral content. They did, however, have one thing in common – clay content.

The clay itself, Young and others researchers have noted, is key. Certain kinds of clay has the power to ease stomach distress. Anyone who’s taken Kaopectate (pre-2003 in the U.S. and any year elsewhere) knows this. It acts as a natural binder to relieve diarrhea and can curb acidity. Bothered by nausea (as many pregnant women are)? Plagued by pathogen-induced diarrhea? It’s little wonder people traditionally sought out clay. It offers inherent medicinal properties.

But that’s not all. Specific clay varieties can actually enhance a person’s or animal’s nutritional potential. The types of geophagic clay ingested by animals and people disable toxic anti-nutrients found in regionally available plants. The knowledge that has been handed down – or instinct that was selected for – allowed people and animals to increase the variety of their diets and likely take advantage of alternative food sources when traditional foods were scarcer during inclement weather, pest infestation, etc. Young’s examination showed that both humans and animals benefitted from geophagy’s ability to counter natural plant toxins. The analysis affirms research done by others who have observed the effect of clay varieties on various natural toxins, including the glycoalkaloids of wild potatoes (PDF) or tannins in acorns.

Experts warn, however, that there’s an increasing danger to this traditional practice. For better and for worse, few if any of us across the globe live in Grok’s world anymore. Agricultural and industrial pollutants have found their way into corners more remote than we could possibly imagine. Even soil in less industrialized countries is bearing the chemical stamp of modernity. One recent study analyzed samples of African soil that was sold for geophagic purposes in various parts of Africa, Europe, and the U.S. Of particular concern to the researchers were the microbe and lead levels. Small levels of mercury and cadmium were also present.

Nonetheless, geophagy continues – in many traditional societies and in more “modern” regions where an increasing number of people are exploring geophagy’s protective and therapeutic effects. I’ve heard that some are using particular clay varieties to treat systemic cases of Candida or Crohn’s. I find the potential of traditionally eaten clays like kaolin, bentonite, and attapulgite – especially for these kinds of applications – compelling. As for obtaining pristine stores or supplements of these varieties, I’m not so won over.

Perhaps some of you in the Primal community practice or know folks who practice geophagy. Maybe you have sources – like the gentleman I met – who you know and trust. Maybe you have personal access to these kinds of clays and have the local resources to get your source thoroughly tested. That would be the way to do it, I’d say.

For the rest of us, there’s this. While it’s clear that geophagy played a role in our species’ evolution, we’re fortunate to have access to good sanitation and an infinite variety of foods that don’t require special formulations to aid digestion. I think there’s value in understanding how our ancestors lived and learned to thrive in their environments. There’s also value, however, in embracing the options we have today.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

I fail to see how this is so “weird”. I take MezoTrace, essentially dirt packed into pill form. I feed there supplement to my horses too. My horses and dogs will dig and lick certain places here and just eat the dirt. I figured it was for the minerals. We do have clay in the soil, though so that makes sense too.

This reminds me of a humorous essay by Roy Blount, Jr.: I Don’t Eat Dirt Personally. “I’m a Southerner who lives in the north,” Blount said, “so I have to explain lots of things. I picked up a New York Times and read: ‘Old Southern Custom of Eating Dirt Seen on the Wane.’ Not as many Southerners are eating dirt as used to.

“I knew I was going to be asked about this at some fashionable soiree, and sure enough a woman with a crew cut came up to me and said, ‘I didn’t know that you ate dirt.’ There are two ways you can go on this. You can either take the Jimmy Carter route and say ‘Well, to tell you the truth there are some perfectly nice folks who do eat clay for digestive reasons, but I personally don’t eat clay and no one in my ­family eats it. And I don’t know anyone who eats clay.’

“But if you go that way, people will say, ‘Here’s a guy who eats dirt and he’s ashamed of it.’ So I would take the Billy Carter approach and say, ‘Hell, yes, we eat dirt! If you haven’t had any blackened red dirt, you don’t know what’s good for you!’ I thought about opening a chain of dirt restaurants. Once it’s been in The New York Times, people will eat it.”

As far as I know, sometimes carnivores eat plant matter to help them throw up and purge their stomachs while other times they eat it to help cleanse their bowels in the same way fibre helps us. I think I might have read that on this site actually.

I remember one time my friend and I were out playing in the forest with his dog and it ate a bunch of bark off of vines. We came back inside and started chasing it around a room and wrestling with it and when my friend was on his back putting the dog in a headlock with his legs it threw up, all over his upper body and face, including in his mouth.

What an interesting article! When I was about three years old, my mother tried houseplants and after seeing the dirt that she had baked in the oven for the plants, I was inspired to eat it. I am told I only took one bite and that was enough for me. It was probably the texture =)

Now, for example when I cut lettuce from my garden, I don’t wash it. There may be a few flecks of dirt, and I make sure there aren’t [m]any bugs and such, but I figure that a little bit of dirt from my land will probably do me a lot of good! However, stuff I get at the farmers market? Yes, I wash, because I don’t know exactly where everything comes from.

And a funny story I forgot to post… our neighbor where we lived last year grew organic veggies in his backyard. He gave some lettuce to a couple college girls renting one of his houses. He later found the lettuce in the garbage and asked them what was wrong with it. They said it had dirt on it so they thought it had gone bad. Guess they were of the breed who thinks veggies grow on grocery shelves.

It’s important to remember that the GI tract is technically entirely “outside” the body. We’re a tube within a tube. So a substance ingested does not enter the body until it crosses the intestinal barrier and into the lymphatic or the circulatory system.

Well Mark, you’ve done it again. So often, I open up your blog, glance at the headline, and think, “What the hell is he talking about now?” but by the end of the article, you have me nodding and saying, “That actually sounds like a decent idea.” Can’t say I’ll be scouring the Internet for edible clay anytime soon, but I sure appreciate the article.

I read your today’s news letter with astonishment; in Europe it is a quite common thing (old home recipe) to eat earth, manly if you have digesting problems or stomach flu. You can buy what the German call Heilerde (Healing Earth) and the French Argile, in almost every pharmacy, you get the stuff in the form of powder, in capsules, or in applicators. A few people eat it also for the mineral content.

Hmmm, I remember as a kid having an overwhelming desire to eat anything clay-like… even play-doh. Although I never did, I did taste it though and it wasn’t terrible. I couldn’t look at it though without salivating.

Haha, I tought I was the only weirdo doing that Paul I loved the smell of play-doh as a kid! I tasted it a couple of times and didn’t like it, but if it was blue, I tried it again and again. Other blue things aswell. It looked so good!

this is such a great post! where i grew up, they would sell clay “cookies” in the marketplace. they were just dried clay shaped into neat forms. they could be eaten dry or boiled in water to make a “soup”.

i would hesitate to eat clay on a daily basis because it IS so effective at drawing things from the colon that some nutrients don’t get absorbed. other than that, some clay (bentonite particularly) is really quite tasty in some water.

This is stone soup. My granddad used to talk about it when I was little, but I never entirely knew what he meant. He used to say that when things were hard “in the old country”, people used to boil up stones for soup, and I used to think “what? Like pebbles?” and be very confused becasue I didn’t understand how you could eat pebbles.

Hello Jenny, I am interested in learning more about where you are from and your experience with geophagy, may it be yourself, family or friends etc… I am an visual artist in the Atlanta area and have recently been learning about geophagy and geophagists and want to explore this subject for my future work. Any information that you could give me would be helpful. Any stories or experiences or contacts. I want to give geophagists a voice and a story that I believe is relevant in my work. I hope that you can help!!

Being a budding geologist since my early teens, I have read about the traditional cultures eating clay back when I was 12 or so. There is a layer of clay in Crima that they call ‘chocolate clays’ that looks almost eadible (it is not nutritious though), so in our hungry student field school years we joked about having some. But I have never experienced the desire to eat clay. I will stick to what grows in the dirt, I think

I used to eat small dirt clumps as a child. Never got sick from it. but it wasn’t clay. It was topsoil. The area had been forest in the past and was cleared for house building. But an area of about a thousand square yards was never developed and a field of wild flowers and weeds grew there. Me and some neighborhood kids would pull some weeds, smooth the dirt, draw a ring and play marbles. We would also eat some of the small clumps of dirt. That time period was from about 1950 to about 56. When I read about all the stuff in refined carbs and modern food, those little dirtballs as we called them, start to look appealing. Great post!

It’s an interesting idea, but I don’t think I’ll be sprinkling dirt on my lentil soup tomorrow. The pollutants, etc. seem like a difficult hurdle to overcome. But maybe there’s a future for dirt farmers.

You mentioned it, but it should be stressed, that “clay” is not “dirt”. Clay beds were laid down sometimes millions of years ago … like salt deposits. If they are in the mountains, they are unlikely to be contaminated by anything. And historically, they were often “baked” which would get rid of parasites. Some clays are way better than others, which is why certain deposits were popular, with both natives and with animals, such as parrots, that eat the clay to neutralize toxic berries.

There is a lot of research on clay use for animals. Clay helps prevent birth defects caused by mycotoxins, and normalizes gut flora for sick cows. But more important, it was pretty much part of everyone’s lives back when … we lived on dirt floors, drank water that was sitting on clay usually. I think the clay DOES interfere with absorptions of some things, but they are the things we don’t get along with, usually. Iron is a weird one, because although we need it, we usually have too much of it unless we have parasites (giving iron supplements to the Maasai makes them more prone to illness).

Anyway, I’ve been taking clay on and off for years, and it’s only done good things. It might cause constipation if you aren’t getting enough fiber (it makes the food digest more thoroughly, so there is less bulk). It has saved many a family member from cases of “food poisoning”. In one case, someone I know was at a retreat where everyone who ate the chicken got very ill. She took her clay, got better in half an hour or so, then dosed everyone else who would take it. They all got better too. It might seem weird, but IT WORKS and it’s cheap.

Growing up we played all day out in the woods, rode our horses and every time we ate something our hands had dirt on them ad we didn’t care, we ate the dirt to, also my dad was a survival instructor in Wash State back in the 70’s& they were taught to eat stuff from the dirt w/out rinsing in off, so I learned that to..Ok, so now I do rinse stuff & wash my hands more, but my mother always told me the reason I don’t have any allergies,don’t have asima & no real health issues is due to eating dirt”not intentional”… So to make a long story short, when I see someone with a baby, I say ” Let them eat dirt” build up that little immune system…

Just now reading “Life on the Mississippi” and Twain talks about the old timers, which would have been early 1800’s, not letting sediment settle in drinking water from the river but stirring it up. Touting benefits much as described. I had not taken it as literal truth,but I suppose it was.

I buy bentonite clay from Mountain Rose Herbs. If you drink it, mix about a teaspoon in a small glass of water, let it sit a few minutes, and drink it, trying to drink the clay itself after it settles, although that’s not necessary because it the water becomes like a colloidal solution, full of trace minerals. But swallowing the clay is beneficial to the digestion. Follow that with anothe glass of water to help it through your body.
You can also use the clay in a bath. Add some hot water, mix about a cup of clay, mix thoroughly to help it dissolve, then add tepid or warm water and soak. This will draw impurities out of your body. Masks work the same way.

I was practicing geophagy but I had know idea there was a name for it! I took bentonite clay for a long time to treat really bad candida when I was a child. I also went off sugar, yeast and wheat at the time. I wish I’d known about Primal back then and I would have cut out all grains! But the clay mixed with caproil and psyllium seed husks really did clean out the system, but I think there must be a less damaging way to do it!

African Elephants eat lots of dirt! Scientists tagged several elephants with trackers and studied their migrational patterns for a year. The elephants had gatherings at specific sites. When the researchers visited these sites, they found barren patches of land. Elephants “mine” the earth for the rich mineral content.

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